The present invention relates to a new and improved method of, and apparatus for, controlling the position of an automatically operated door as a function of the presence and movement conditions of at least one person present on a support surface within a predeterminate space extending on a predetermined side of the automatically operated door.
It is known in the art to utilize ultrasound, radar and video systems for such purpose. Radar systems as well as video systems are considered expensive and complicated and thus are believed to be inadequate for utilization in connection with the aforementioned door control function.
In an opto-electrical apparatus for monitoring predetermined spatial regions such as known, for example, from Swiss Patent No. 607,187, published on Nov. 30, 1978, there are provided an objective lens, a prismatic screen or grid which can be uni-axially or bi-axially displaced, groups of receivers or detectors and an evaluation circuit. The prismatic screen or grid constitutes a movable, location-related filter for alternatingly guiding light originating from points or limited areas of the object to be imaged or monitored, to the groups of receivers or detectors. Objects or persons entering the space which is swept or scanned by the monitoring or sensing apparatus affect the zero interference pattern which is generated in the absence of such objects or persons, and thereby cause a signal to appear above the zero level.
It is one disadvantage of such monitoring system that expensive optical components are required as well as mechanical drive means and difficult adjustments have to be carried out. Also, the proper function of such monitoring system is impaired by interfering influences of light.
In a similar lift or elevator control system such as known, for example, from British Published Patent Application No. 2,093,986, published on Sept. 8, 1982, there are also provided various optical components and an electronic evaluation circuit. One of the optical components constitutes a spatial filter which, in one illustrated embodiment, has a semi-spherical facetted or poly-face shape.
This lift or elevator control system operates in the spectral region of normal visible light so that spurious or interfering light influences cannot be precluded. Likewise, relatively expensive optical components are incorporated into the system and, due to mutually antagonistic requirements, such system cannot be adjusted in a simple manner.